Colour biases are a question of taste

Abstract

Unpalatable insects often advertise their defences to avian predators by conspicuous colours, such as red and yellow. Therefore, perhaps not surprisingly, birds tend to have unlearned biases against warningly coloured food. These biases are particularly evident when other components of insect warning displays, such as novel sounds and odours, are also present. We tested whether bitter taste, often associated with the defensive chemicals used by aposematic insects, can elicit or enhance specific colour aversions to red and yellow food in young domestic chicks, Gallus gallus domesticus. In our first experiment, subjects were given familiar brown chick crumbs sprayed with either a 0, 1, or 4% quinine solution. In each palatability treatment, chicks were then offered a choice of palatable crumbs that were coloured either red and green or yellow and green. Chicks attacked (pecked or ate) fewer red and yellow crumbs and more green crumbs with increasing quinine concentrations. Chicks also ate fewer red and yellow crumbs with increasing unpalatability, although there was no effect on the numbers of green crumbs eaten. In a second experiment, we gave chicks a colourless drop of either 0 or 0.3% quinine solution and found that this also produced similar attack biases against red and yellow as is in the first experiment. Taken together, these results show that birds use unpalatable taste to adapt their visual foraging decisions, which has consequences for the evolution and stability of mimicry systems, and also has implications for the pairing of colour and taste in psychological experiments.

Eating with our eyes: From visual hunger to digital satiation

“…In fact, it has been suggested that trichromatic colour vision may originally have developed in primates as an adaptation that facilitated the selection of more energy-rich (and likely red) fruits from in-amongst the dark green forest canopy (e.g., Bompas, Kendall, & Sumner, 2013;Regan et al, 2001;Sumner & Mollon, 2000). Certainly, a complex interplay of animal signalling designed to capture the attention (often visual) of pollinators and/or repel predators has been a central part of the co-evolution of both the visual systems of animals and the colouration schemes utilized in both the animal and plant kingdoms (e.g., see Barth, 1985;Cott, 1940;Poulton, 1890;Rowe & Skelhorn, 2005;Schaefer & Schmidt, 2013).…”

Food color, flavor, and conditioned avoidance among red-winged blackbirds

“…Alternatively (hypothesis 2), based on the neural convergence hypothesis [1] -vagal afferents mediating gustatory and visceral sensations -and the cue-consequence [19] and skin-gut specificity [20] of conditioning contingencies, we predicted blackbirds would avoid flavors previously paired with negative postingestive consequences. Finally, foraging biases [21] and baseline preferences affect conditioned avoidance (hypothesis 3). Thus, relative to preferred colors and flavors, we predicted that blackbirds would avoid colors and flavors for which baseline indifference or aversion existed.…”

Birds select conventional over organic wheat when given free choice

“…However, more recent studies have shown certain species of bird to respond to a number of taste stimuli, particularly bitter tastes in foodstuffs and solutions. 31,32 However, the marked delay in formation of preference observed in the present study is more indicative of a post-ingestive effect of food consumption than of a simple taste preference, where the response would likely be much more rapid. Taste is unlikely, therefore, to be driving the preference for conventional wheat in the current experiment.…”